U.S. patent application number 09/919426 was filed with the patent office on 2003-02-20 for forged article with prealloyed powder.
Invention is credited to Ilia, Edmond.
Application Number | 20030033904 09/919426 |
Document ID | / |
Family ID | 25442060 |
Filed Date | 2003-02-20 |
United States Patent
Application |
20030033904 |
Kind Code |
A1 |
Ilia, Edmond |
February 20, 2003 |
Forged article with prealloyed powder
Abstract
These connecting rods are made from prealloyed manganese,
sulfur, ferrous based powder. The prealloyed powder then is mixed
with copper and carbon. The copper content is at higher than normal
copper contents. The resulting forged connecting rods had an
improvement in tensile strength and an improvement in fatigue
strength.
Inventors: |
Ilia, Edmond; (Ridgway,
PA) |
Correspondence
Address: |
EMCH, SCHAFFER, SCHAUB & PORCELLO CO
P O BOX 916
ONE SEAGATE SUITE 1980
TOLEDO
OH
43697
|
Family ID: |
25442060 |
Appl. No.: |
09/919426 |
Filed: |
July 31, 2001 |
Current U.S.
Class: |
75/252 ;
420/76 |
Current CPC
Class: |
B22F 2998/00 20130101;
B22F 2998/00 20130101; F16C 7/023 20130101; B22F 3/17 20130101;
B22F 5/10 20130101; C22C 33/0207 20130101 |
Class at
Publication: |
75/252 ;
420/76 |
International
Class: |
C22C 038/60 |
Claims
I claim:
1. A powder useful for producing forged articles comprising a
mixture of the prealloyed manganese, sulfur, ferrous based powder,
copper and carbon wherein the mixture has a copper content higher
than standard copper contents.
2. A powder according to claim 1 comprising by weight percent:
5 Component Weight Percent copper (Cu) 2.0 to 5.0 carbon (C) 0.2 to
1.0 prealloyed Mn S ferrous based powder balance
3. A powder according to claim 1 comprising:
6 Component Weight Percent Cu 2.5 to 4.5 C 0.2 to 0.7 prealloyed Mn
S ferrous based powder balance
4. A powder according to claim 1 comprising:
7 Component Weight Percent Cu 3.0 to 4.0 C 0.4 to 0.7 prealloyed Mn
S ferrous based powder balance
5. A forged article produced from the prealloyed powder of claim
1.
6. A forged connecting rod produced from the prealloyed powder of
claim 1.
Description
TECHNICAL FIELD
[0001] This invention relates to forged articles made from ferrous
powder prealloyed with manganese and sulfur. More specifically, the
forged articles are forged engine connecting rods.
BACKGROUND OF THE INVENTION
[0002] The connecting rod manufacturing process involves pressure
molding metal particles in a closed mold under significant pressure
to produce a green compact form of the rod. Next, the green compact
is heated in a furnace sufficiently to form a sintered preform in
which metal particles are bonded. Next, the sintered preform is hot
forged to final rod shape which increases the rod's density and
strength. The automobile industry continues to challenge connecting
rod manufacturers to increase the fatigue strength of these
articles. As a result, higher performance materials are needed for
forged connecting rods. The goal is to engineer a powder metal
blend to manufacture connecting rods with the following
characteristics: high strength; good machinability; reasonable
cost, good weight and dimensional control. Our research included
materials considerations; metallurgical and microstructure
evaluation; dimensional change measurements; tensile strength;
fatigue strength and machinability tests.
BRIEF SUMMARY OF THE INVENTION
[0003] The forged articles or connecting rods of this invention are
made from ferrous based powder prealloyed with manganese and
sulfur. The prealloyed powder then is admixed with copper at higher
than normal copper contents. Materials considered were as follows.
In a first approach, I thought that increasing Cu content from 2%
to 3% or even 4% would improve the strength of connecting rods for
the following reasons: Cu strengthens the ferrite, Cu hardens the
ferrite, and Cu hinders grain growth after forging. In a second
approach I thought that using prealloyed MnS base powder, instead
of admixed MnS base powder, would improve the strength of
connecting rods for the following reasons: smaller inclusion (MnS)
size, uniform inclusion (MnS) distribution, and higher Mn
content.
[0004] As a result, I used a commercially available prealloyed
manganese, sulfur, ferrous based powder for producing the forged
article. The prealloyed powder then is mixed with copper and carbon
to produce a mix comprising by weight percent:
1 Component Weight Percent copper (Cu) < 2.0 to 5.0 carbon (C)
0.2 to 1.0 prealloyed MnS powder balance
[0005] The resulting forged connecting rods had an improvement in
tensile strength and an improvement in fatigue strength.
BRIEF DESCRIPTION OF THE DRAWINGS
[0006] FIG. 1 is a perspective view of a forged connecting rod.
DETAILED DESCRIPTION OF THE INVENTION
[0007] The methods for preparing the prealloyed powder may vary
widely. Typically, the powder is prepared by atomization of a
molten metal stream of iron, manganese and sulfur. The resulting
particles usually have an irregular spherical shape. To facilitate
compaction, the atomized particles can be collected after
solidification and subjected to annealing at 1700.degree. F. for
about 11/2 hours, followed by grinding to break up particle cakes,
and then passed through an 80 mesh sieve.
[0008] The prealloyed ferrous powder then is mixed with copper and
graphite at room temperature. The copper powder generally has a
purity of 99%. The copper powder and carbon (graphite flake
powder), however, are commercial grade materials. The copper powder
is mixed in a range of 2.0 to 5.0% by weight of the mixture. The
graphite powder is added to yield a final carbon content in the
product ranging from 0.2 to 1.0 weight percent.
[0009] FIG. 1 illustrates forged connecting rod 10. Rod 10 has an
elongated configuration extending along longitudinal axis A-A. Rod
10 includes midportion 12; small end portion 14; and large end
portion 16. Bore 18 is formed through small end portion 14 adapted
to receive a wrist or piston pin (not shown) as is well known in
the engine art. Aperture 20 is formed through large diameter end 16
and is adapted to receive a journal of a crankshaft (not shown) as
is well known in the engine art. Large end portion 16 has a side
thrust face 22. Rod 10 includes large end portion 16 having a pair
of oppositely facing edges or end surfaces 24. In the particular
design of the connecting rod shown in FIG. 1, side thrust face 22
is in a raised plane with respect to the remaining side surface 26.
Side thrust face 22 also includes a pair of radially outwardly
extending portions 28, 30 located to either side of aperture 20.
Portions 28, 30 extend radially outward from aperture 20 and
terminate at end of edges 24.
[0010] FIG. 1 also shows a pair of slits or creases 32, 34 formed
in the side thrust face including extensions 28, 30. Each crease
32,34 is arranged to one side of aperture 20 and they are
substantially aligned across aperture 20. Creases 32, 34 extend
inwardly from surfaces 28, to a considerable depth as is evident by
examination of leftward end 24 and the cylindrical surface which
forms the bore 20.
[0011] The manufacturing processes for making the connecting rod
may vary widely. For example, a green compact is made in the form
of the rod by molding powder metal particles in a closed mold under
great pressure, typically about 80,000 psi. This pressure molding
causes the particles to mechanically interlock and form a stable,
relatively weak part but strong enough for handling. Next, the
green compact is heated in a furnace at temperatures higher than
2000 degrees F. for a period of time sufficient to cause the metal
particles to bond. After sintering, the preform has the same
configuration as the green compact but is much stronger.
[0012] The preform then is hot forged to achieve the shape and
increase density and strength as required for a connecting rod.
Typically, it is hot forged in a press at a pressure of about
60,000 psi and at a temperature of about 1800 degrees F.
2 Component Weight Percent Preferably, the mixture of this
invention comprises: Cu 2.5 to 4.5 C 0.2 to 0.7 prealloyed MnS
powder balance More preferably, the mixture is: Cu 3.0 to 4.0 C 0.4
to 0.7
[0013] prealloyed MnS powder balance
[0014] The mixed powder of this invention may be used to forge
articles other than connecting rods. Other automotive uses include
piston rings and valve seats for internal combustion engines. Other
parts include clutch races, differential gears and similar
parts.
[0015] The following Examples further illustrates the composition
of this invention.
EXAMPLE I
Prior Art
[0016] The following shows average tensile results for standard
production powders with varying amounts of copper. Results for a
standard manganese sulfur admixture (rather than the prealloyed
powder of this invention) also are shown. The average is based on 6
runs.
3 TENSILE RESULTS Commercial Grade Prealloyed Mn S Standard
Production Powder Powder 2% Cu 3% Cu 4% Cu 2% Cu (psi) (psi) (psi)
(psi) Avg. 124,534 144,788 145,046 120,268 StDev 3,641 2,771 3,805
1,755
EXAMPLE II
Prior Art
[0017] The following shows fatigue results for standard production
powders with varying amounts of copper. Results for a standard
prealloyed manganese sulfur powder also are shown.
4 FATIGUE RESULTS Commercial Grade Standard Prealloyed production
powder Mn S Powder 2% Cu 3% Cu 4% Cu 2% Cu (ksi) (ksi) (ksi) (ksi)
Endurance Limit @ 50% 45.21 52.63 52.64 50.77 Scatter 1.07 2.18
2.10 1.88 Standard deviation (s) 0.28 0.49 0.49 0.43
EXAMPLE III
[0018] Tensile Results for the prealloyed Mn S ferrous powder of
this invention with 3% Cu show an improvement of approximately 5%
in tensile strength compared to standard production.
EXAMPLE IV
[0019] Fatigue results for the prealloyed Mn S ferrous based
powders of this invention with 3% Cu show an improvement of 19% in
fatigue strength compared to standard production.
[0020] In addition to these embodiments, persons skilled in the art
can see that numerous modifications and changes may be made to the
above invention without departing from the intended spirit and
scope thereof.
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